title: Effects of lower-leg rhythmic cuff inflation on cardiovascular autonomic responses during quiet standing in healthy subjects.
abstract: To determine the effects of muscle pump function on cardiac autonomic activity in response to quiet standing, we simulated the muscle pump effect by rhythmic lower-leg cuff inflation (RCI) with four cuff pressures of 0 (sham), 40, 80, and 120 mmHg at 5 cycles/min. The R-R interval (RRI) and beat-to-beat blood pressure (BP) were acquired in healthy subjects (6 males and 5 females, aged 21-24 yr). From the continuous BP measurement, stroke volume (SV) was calculated by a pulse-contour method. Using spectral and cross-spectral analysis, RRI and systolic BP variability as well as the gain of spontaneous cardiac baroreflex sensitivity (sBRS) were estimated for the low- and high-frequency (HF) bands. Compared with the sham condition, RCI with cuff pressures of 80 and 120 mmHg led to increases in the mean RRI (P < 0.01) and HF power of RRI fluctuation (P < 0.05 for 80 mmHg and P < 0.01 for 120 mmHg) during quiet standing. Reduction in SV during standing was suppressed, and the sBRS of the HF band for standing were increased by RCI for either cuff pressure (P < 0.05 for 80 mmHg and P < 0.01 for 120 mmHg). However, at 40 mmHg RCI, these remained unchanged. These results suggest that, during standing, RCI of the lower leg increases cardiac vagal outflow when the cuff pressure is raised enough to oppose the hydrostatic-induced venous pressure in the calf.
authors.affiliation: Department of Bio-System Engineering, Graduate School of Science and Technology, Yamagata University, Yonezawa, Japan. nzq@yz.yamagata-u.ac.jp
authors.forename: Kyuichi
authors.initials: K
authors.lastname: Niizeki
authors.forename: Takanori
authors.initials: T
authors.lastname: Tominaga
authors.forename: Tadashi
authors.initials: T
authors.lastname: Saitoh
authors.forename: Izumi
authors.initials: I
authors.lastname: Nishidate
authors.forename: Tatsuhisa
authors.initials: T
authors.lastname: Takahashi
authors.forename: Katsuo
authors.initials: K
authors.lastname: Uchida
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D011187:Posture / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology